Spark-plug.



H. J. FARRELL & F. A. ARDRON.

SPARK PLUG.

APPLICATION FILED MAY 23', I914.

1,139,654. Patented May 18, 1915.

WITNESSES: l/V l/E IV TORS 6- PM. Paymo/m J 75/76// RAYMOND J. FARRELL ANDjFAY A. ARDRON, OF SEATTLE, WASHINGTON.

SPARK-PLUG.

Application filed May 23, 1914.

To all whom it may concern Be it known that we, RAYMOND J. FAR- BELL and FAY A. ABDRON, citizens of the United States, residing at Seattle, in the county of King and State of Washington, have invented certain new and useful Improvements in Spark-Plugs, of which the following is a specification.

, In the accompanying drawings, Figure 1.

is a longitudinal section of our improved spark-plug in its preferred form. Fig. 2 is a side elevation of the same; and Fig. 3 is an underside end view thereof.

In carrying out the invention, we provide a shell 5, preferably of steel, having at its lower end an external screw-thread 6 for engaging in a threaded hole provided in an engine-cylinder. Said shell is bored from the top to afiord a chamber 7 which terminates at an annular shoulder 8 and below the latter is an extension 9 having a contracted lower end which terminates at the mouth 10. At its upper end the chamber 7 is screw-threaded, as at 11.

The shell '5 constitutes the outer electrode of the plug and the inner electrode is formed of a rod 12 which is screw-threaded at the top and at its lower end, is provided with a relatively large head 13. formed substantially rectangular in horizontal section and is further characterized by having slots 14: and 14} extend diametrically therethrough to furnish a plurality of prongs 15 which may be spread apart to regulate the spaces or gaps between the outer corners 16 of the electrode-head and the opposing rim 17 of the other electrode.

As customary in spark plugs, the inner electrode or rod 12 extends axially through a sleeve 18 of porcelain, or an equivalent insulating material. In this instance, the sleeve 18 extends through a tubular casing 19 which is desirably made of brass, although any other suitable metal may be used instead. Said casing is formed with a body Specification of Letters Patent.

The latter is Patented May 18, 1915.

Serial No. 840,419.

of a diameter to fit in the chamber part 9 and through the bore of a securing nut 20 which engages the screw-threads 11. The casing 19 is furthermore provided with a peripheral ridge 21 adapted to fit within the chamber 7.

22 and 23 represent washers of a yielding material, such as asbestos, which are interposed between the ridge 21 and the shoulder 8 and nut 20, respectively. Another washer 24 of similar material is employed between the lower end of the casing 19 and a collar 18 formed integral with the sleeve 18 at its lower end. A washer 25 of similar character is likewise utilized between the electrode-head 13 and the sleeve 18, said head and the associated. washer being advantageously accommodated in a recess 19 provided in the sleeve whereby lateral movement of the head 13 is prevented.

The sleeve 18 is of a length to extend above the casing 19 and surrounding the protruding end of the sleeve is a ring 26 of an insulating material, such as asbestos, and a washer 27 surmounts the sleeve as shown in Fig. 1. The external diameters of the ring 26 and washer'27 are, by preference, equal to the corresponding diameter of the casing 19. Fitted over the washer 27 and extending down below the interstice between the ring 26 and the casing is acap 28 of a tough insulating material such as conventionally known as fiber. This cap not only serves to prevent the admission of moisture through the referred to interstice, but also serves to protect the asbestos elements 26 and 27 from being destroyed by being abraded or knocked off when struck by a wrench or other article.

29 represents a metal washer which serves as a seat for a clamping nut 30 which engages the screw-threads of the rod 12.

31 is a binding nut for connecting a circuit wire to the rod.

According to the present invention, the porcelain sleeve 18-is inclosed by a metal casing 19 and the cap 28 thereby obviating any danger from water coming in contact with the sleeve to cause the same to break when hot. Furthermore, the casing 19 be-- ing formed of a material having a high conductivity for heat, will not cause the sleeve to become unduly hot when operating. The insulation afforded by the porcelain sleeve and the elements 26 and 27 is such that there is no danger of short-circuiting of the current and particularly as the referred to elements are prevented by the cap 28 from absorbing moisture.

To clean the electrodes, or for regulating their relative positions, the plug is removed as a whole from the cylinder with Which'it is employed, whereupon the inner electrode, or rod, l2 is adjusted by means of the clamping nut 30, the washer 25 ordinarily accommodating itself to the changed position of the head or where the adjustment is considerable, a new Washer of suitable thickness may be. substituted for the one in use.

What we claim, is

1. In a spark-plug of the class described, the combination with a shell forming one electrode, a rod forming the other electrode of the device, of an insulating sleeve surroundingsaid rod, a metal casing surrounding said sleeve and extending from within said shelltoa short distance below the top of the sleevi'e, means cooperating with said rod for securing the latter to the sleeve and also serving to secure the sleeve to the casing, means for securing the casing to the shell, and a cap overlapping the upper end of the casing serving as a cover for the up per ends of the sleeve and casing to close the interstice between the same.

2. In a spark-plug of the class described, the combination with a shell forming one electrode, and a rod forming the other elec-' trode of the device, of an insulating sleeve surrounding said rod, a metal casing surrounding said sleeve and extending from Within said shell to a short distance below the top 1 of the sleeve, .means cooperating With said rod for securing the latter .to the sleeve and also-serving to secure the sleeve to the casing, means for securing the casing to the shell, and a cap overlapping the upper end of the cas'in serving as a cover for the upper endsof t e sleeve and'casing to close the interstices-between the same.

3. In a spark-plug of the class described, a shell constituting one electrode, a screwthreaded rod having an enlarged head and serving for theother electrode, a porcelain sleeve inclosing said rod and provided at one end with a recess to accommodate the head thereof, a metal casing inclosing said sleeve and extending into said shell, a nut engaging a screw-thread provided in the shell for coupling the casing to the latter, means superposed on said casing for insulating the sleeve with respect to said rod, a cap provided to cover such insulating means and likewise the interstice between said means and the casing, and a clampin nut engaging the screw-threads of the ro for securing the same within the sleeve.

Signed at Seattle, Wash, this 18th day of May, 1914c.

.RAYMOND J. FARRELL.

FAY A. ARDRON.

Witnesses HORACE BARNES, E. PETERSON. 

